Extradural pain relief in labour: bupivacaine sparing by extradural fentanyl is dose dependent

• Published in: British journal of anaesthesia : BJA Vol. 78; no. 5; pp. 493 - 497
• Main Authors: Lyons, G, Columb, M, Hawthorne, L, Dresner, M
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.05.1997; Oxford University Press; Oxford Publishing Limited (England)
• Subjects: Adolescent; Adult; Analgesia, Epidural - methods; Analgesia, Obstetrical - methods; Analgesics; Analgesics, Opioid - administration & dosage; Analgesics, Opioid - adverse effects; Anesthetics, Local - administration & dosage; Biological and medical sciences; Bupivacaine - administration & dosage; Dose-Response Relationship, Drug; Double-Blind Method; Drug Combinations; Female; Fentanyl - administration & dosage; Fentanyl - adverse effects; Humans; Medical sciences; Neuropharmacology; Pharmacology. Drug treatments; Pregnancy; Pruritus - chemically induced; Human; Fentanyl; Opiates; Labour; Narcotic analgesic; Dose activity relation; Local anesthetic; Analgesia; Chemotherapy; Regional anesthesia; Bupivacaine; Pain; Treatment; Extradural administration; Female; Drug interaction; Delivery; Anilide
• ISSN: 0007-0912; 1471-6771
• DOI: 10.1093/bja/78.5.493

The minimum local analgesic concentration (MLAC) of bupivacaine in labour is defined as the effective concentration in 50% of subjects (EC50). We have used the technique of double-blinded sequential allocation to quantify the bupivacaine sparing effect of the addition of four different doses of extradural fentanyl in 223 labouring women. There were five groups: (1) plain bupivacaine (control); (2) bupivacaine with fentanyl 1 microgram ml-1; (3) bupivacaine with fentanyl 2 micrograms ml-1; (4) bupivacaine with fentanyl 3 micrograms ml-1; and (5) bupivacaine with fentanyl 4 micrograms ml-1. The MLAC of bupivacaine were 0.069% w/v, 0.057% w/v, 0.048% w/v, 0.031% w/v and 0.015% w/v, respectively. We observed a reduction in MLAC of 18%, 31% (P = 0.03%), 55% (P < 0.0001) and 72% (P < 0.0001) with fentanyl 1, 2, 3 and 4 micrograms ml-1, respectively, demonstrating a significant negative linear trend (P < 0.0001) with increasing fentanyl dose. The incidence of pruritus was increased significantly with fentanyl 4 micrograms ml-1 (P = 0.0015). Because of this, fentanyl 3 micrograms ml-1 may be the optimal dose when the aim is bupivacaine sparing extradural analgesia during labour.